My overall program is to improve the efficiency and sustainability of New York dairy farms. Ths is approached conducting research amd providing information to adjust dairy cattle rations. These adjustments are targeted to improve the efficiency of nutrient use within the animal and decrease nutrient excretion to the environment. One tool used to do this is the Cornell Net Carbohydrate and Protein System(CNCPS) model. The current primary research focus is on nitrogen use and metabolism.